As wireless network technologies have made progress, people can surf on the Internet to find and discover information and download the contents such as files, songs, and videos, anytime, anywhere by using a variety of mobile communication terminal such as cellular phones, smartphones, and tablet computers.
As shown in FIG. 1, a user who uses a mobile communication terminal 10 capable of data communication to get data on a network, commonly sends/receives requests for the data, e.g., web page, to/from a web server 12a by using a browser 10a. During the course of reception of a web page from the web server 12a (S01), a socket is created by an operating system (OS) in request of the browser 10a, with its source address set to an access address, e.g., an IP address, which is allocated from a network 11 to which the mobile communication terminal 10 is connected, and with its destination address set to the web server 12a. A socket is a logical object indicating an endpoint of inter-process communication flow in a computer network, consisting of protocol, originating IP address and port number, and destination IP address and port number. Then, with the created socket, a socket-to-socket virtual connection, called a session, to the web server 12a is established through the network 11. The network 11 can be a cellular CDMA2000 or W-CDMA network, a high-speed local network, e.g., Wi-Fi network, or a different type network.
Once a content item in the web page received is chosen, a data send request, for example, a hyper-text transfer protocol (HTTP) request is sent, through a session established by the OS, as described above, to a content server 12b (S02). Upon reception of the HTTP request, the content server 12b sends an HTTP response, in download or streaming mode, to the mobile communication terminal 10 (S03). Once the HTTP response is received, an application, for example, player 10b is invoked that is associated with the content type specified in the multipurpose internet mail extensions (MIME) header in the HTTP response. Then, the content data contained in the HTTP response starts to be rendered by the application.
By the way, wireless network conditions often change with time and location, compared with wired networks. It is even more so for Wi-Fi networks which cover local areas only. Hence, changing network conditions may cause the mobile communication terminal 10 to be disconnected from the network 11, while the mobile communication terminal 10 is communicating with remote servers. If the network disconnection happens, the OS checks if there is a new network connectible, and if so, is assigned a new IP address from the network found. The socket, which was created with its source address set to the no-longer-valid IP address, gets useless, and thereby the applications sending/receiving data through the socket, e.g., the browser 10a or player 10b come to halt. In this case, after a new IP address has been assigned, the above-mentioned operations for a new connection such as socket and session creation are conducted again, by request of user after some interval or after being notified of a particular symbol displayed on display panel by the OS of the terminal 10. As a result, the content intended by the user is received.